Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$195.78	11.470%	$218.236	$218.24	$218.25	$218.20
Purchase #2	$86.78	6.717%	$92.609	$92.61	$92.60	$92.60
Purchase #3	$33.87	4.613%	$35.4324	$35.43	$35.45	$35.40
Purchase #4	$120.55	8.620%	$130.9414	$130.94	$130.95	$130.90
Purchase #5	$233.97	8.537%	$253.944	$253.94	$253.95	$253.90
Purchase #6	$250.72	7.488%	$269.4939	$269.49	$269.50	$269.50
Purchase #7	$72.91	12.559%	$82.0668	$82.07	$82.05	$82.10
7 purchase totals =	$994.58		$1,082.7235	$1,082.72	$1,082.75	$1,082.60